The throwing blades must be removable since they wear out and must be routinely replaced. The mounting must provide for accurate location on the wheel radially since varying of the radial position can result in a wheel imbalance when rotated at high speed. Excessive clearance can result in tipping of the blade and irregular performance.
The throwing blades must be removable since they wear out and must be routinely replaced. The mounting must provide for accurate location on the wheel radially since varying of the radial position can result in a wheel imbalance when rotated at high speed. Excessive clearance is a result in tipping of the blade and irregular performance.
In addition, any clearance spaces can result in abrasive material entering those spaces and make it difficult or impossible to remove the blade for replacement.
U.S. Pat. No. 5,476,412 describes a method using a tapered dovetail channel to create a tight fit which wedges to locate the blade radially. However, the tapered dovetail is difficult to form accurately by normal casting processes and accuracy of the radial location of the blade may suffer if there are inaccuracies in forming the double tapered dovetail shape. These radial location variations are problematic as described above.
Another approach which is described in U.S. Pat. No. 3,869,289 involves the use of springs to force the blade axially out to bring dovetail wings on the blade into engagement with the dovetail shaped channel sides in the wheel. This requires separate spring elements which can get broken and lost. Proper locking sometimes is not achieved with this design.
It is an object of the present invention to provide a throwing blade mounting to the throwing wheel which does not require precision forming of a double tapered wedge shape in a dovetail but rather uses a simpler shape which is easier to machine and to obtain accurate radial location of the blades on the wheel side plates.